Solid-electrolyte interphase (SEI) growth happens continuously once lithium-ion batteries (LIBs) are produced and it is regarded as one of the most important degradation factors of LIBs. Therefore, one important way to increase the accuracy of physics-based battery life models is to consider as many direct or indrect effects of SEI growth as possible. These effects should include at least: 1) the consumption of lithium ions; 2) the consumption of solvent components, e.g. ethylene carbonate (EC) and dimethyl carbonate (DMC); 3) the generation of the porous (e.g. (CH2OCO2Li)2) and dense (Li2CO3) components, and therefore thickening of the SEI layers. Previous models have captured the consumption of lithium ions, which further induces loss of lithium inventory and capacity loss. Thickening of SEI layers has also been included, which further causes porosity reduction of the anodes and resistance increase. However, the consumption of solvent components has largely been omitted.
Therefore, we aim to fill the above research gap by considering, for the first time, the electrolyte volume as an independent variable, and addressing concentration change and electrolyte dry-out in the physics-based battery life model. This will be a significant contribution to more comprehensive discussions on the possible non-linear capacity loss at end of life of LIBs.